This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-375038, Dec. 28, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a magnetic write/read apparatus for magnetically writing/reading information and a magnetic recording medium used in the same and, more particularly, to a head load/unload scheme magnetic write/read apparatus having a contact type head slider mounted on it with a head which comes into contact with the surface of a magnetic recording medium in the write/read mode and which is retreated outside the magnetic recording medium in the non-read/write mode, and a magnetic recording medium used in the same.
As a means for improving the recording density of a magnetic write/read apparatus, the spacing between the head and disk may be decreased. In recent years, transition of the magnetic write/read apparatus from one with a flying type head, with which a write/read is performed while keeping the head to fly from a rotating magnetic disk, to one with a contact type head, with which the head is brought into continuous contact with a rotating magnetic disk, has been studied in order to further decrease the spacing between the head and disk.
With the former apparatus, an error occurs in the flying height depending on the individual difference and variations in attaching the head, and the like. A spacing is accordingly formed between the head and disk by an amount corresponding to the head flying height and its error. This spacing can be decreased only limitedly. With the latter apparatus, the spacing between the head and disk can be decreased as it can be as small as an amount corresponding to the roughness of the head and disk. Nevertheless, the latter scheme has not been realized due to the problems of the wear and dynamic stiction of the head.
An example of the head operating scheme of the magnetic write/read apparatus includes the CSS scheme and the load/unload scheme. With the CSS scheme, when the head is not in the write/read mode, it has been landed on the inner circumference of the stationary disk. In order to increase the recording density of the magnetic write/read apparatus, the spacing between the head and disk must be decreased, and the surface roughness of the head and disk must be decreased for this purpose. When, however, objects with a small surface roughness come into contact with each other, because of the lubricant and water vapor on the disk which exist between the head and disk, a force for attracting the head and disk to each other is generated to cause stiction. In the CSS scheme, the head is landed on the stationary disk, causing static stiction. Due to this static stiction, an excessive force acts on the head during starting. Then, the starting operation of the head may become unstable, and the spindle motor may become unable to operate.
In order to solve these problems, the load/unload scheme may be raised. With the load/unload scheme, when the head is not in the write/read mode, that is, when the disk does not rotate, the head has been retreated from above the disk onto a ramp outside the disk, and does not land on the stationary disk. Thus, when the load/unload scheme is used, static stiction does not occur. In a magnetic write/read apparatus using a flying type head, the disk and head come into continuous contact with each other only in the non-write/read mode. Thus, static stiction is avoided by employing the load/unload scheme. In the magnetic write/read apparatus using a contact type head, however, the head comes into continuous contact with the rotating disk in the write/read mode, thus causing dynamic stiction. When this dynamic stiction occurs, variations in stiction force of the traveling head excite vibration of the head, causing the head to jump.
A technique aiming at prevention of static stiction between a disk and head, which uses both the CSS scheme and the flying scheme, has conventionally been studied. For example, according to one method, in order to decrease the head flying height, the surface roughness of the disk is decreased on the data zone, while its CSS zone has an artificial texture, thereby preventing static stiction. According to another method, in order to decrease the landing area of the head, an stiction preventive pad is formed on the air bearing pad. These methods aim at avoiding static stiction occurring when the head is landed on a stationary disk. With the structure as described above, the surface roughness of the disk is increased, or that of the head is increased. However, from the viewpoint of prevention of dynamic stiction in the write/read mode of a contact recording type head, these methods cannot be employed because they increase the spacing undesirably. If disks have the same surface shape, the static stiction force is larger than a dynamic stiction force. Hence, even among disks having such a large static stiction force that they cannot be used with the prior art, some do have a dynamic stiction force only at an acceptable level. In addition, this dynamic stiction occurs while the disk rotates. Therefore, this stiction state cannot be specified easily.
It is the first object of the present invention to provide a magnetic recording medium which does not cause dynamic stiction even if a head contact slides with it, and accordingly can be written and read well.
It is the second object of the present invention to provide a magnetic write/read apparatus the head of which does not cause a jumping phenomenon due to dynamic stiction even if it comes into slidable contact with a magnetic recording medium, and accordingly can write/read well.
First, the present invention provides a magnetic recording medium, comprising,
a magnetic layer on which information is readed by a magnetic head,
a protective layer formed on the magnetic layer, wherein the protective layer having a surface with which a magnetic head comes into contact to generate a static stiction force on the surface, the static stiction force is not more than 250 gf/mm2.
Second, the present invention provides a magnetic recording medium, comprising,
a magnetic layer on which information is readed by a magnetic head,
a protective layer formed on the magnetic layer;
wherein the protective layer having a plurality of asperities on a surface and satisfying Rxe2x88x929709/N less than 6.6, when a load area ratio is not more than 5%, where N is the number of asperities per xcexcm square and R (nm) is an average of currature radius of peaks of the asperities.
Third, the present invention provides a magnetic write/read apparatus comprising
a magnetic recording medium according to the first or second invention, and driving means for supporting and rotationally driving the magnetic recording medium,
a head slider mounted with a head to write/read information on/from the magnetic recording medium;
a ramp member for causing the head slider to escape from above a surface of the magnetic recording medium and holding the head slider, and
head actuator means for supporting the head slider, loading the head slider from the ramp member to above the surface of the magnetic recording medium, and unloading the head slider from above the surface of the magnetic recording medium to the ramp member.
According to the present invention, a magnetic recording medium can be obtained, which does not cause dynamic stiction even if a head comes into slidable contact with it, and accordingly can be written and read well.
According to the present invention, a magnetic write/read apparatus can be obtained, the head of which does not cause a jumping phenomenon due to dynamic stiction even if it contact slides with a magnetic recording medium, and accordingly can write/read well.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.